Chronometric recorder



Jan. 24, 1950 w. K. CQBURN CHRONOMETRIC RECORDER 6 Sheets-Sheet 1Original Filed March 30, 1946 INVENTOR ZfZamfg/m.

ATTORNEY Jan. 24, 1950 w. K; COBURN CHRONOMETRIC RECORDER 6 Sheets-Sheet2 Original Filed March 30, 1946 a in? .m @m. Er

ATTORNEY Jan. 24, 1950 w. K; COBURN I 2,495,552

CHRONOMETRIC RECORDER Original Filed March 30, 1946 6 Sheets-Sheet 3INVENTOR F 5 Jazz/2M f @2542.

ATTORNEY Jan. 24, 1950 w. K. COBURN CHRONOMETRIC RECORDER 6 Sheets-Sheet4 Original Filed March 50, 1946 INVENTOR. BY M Z'aW/G Q50, 7 7M?) Jan,24, 1950 w. K. COBURN 2,495,652

CHRONOMETRIC RECORDER Original Filed March 30, 1946 6 Sheets-Sheet 5 wwm7 4 QM any W Jan. 24, 1950 w. K. COBURN CHRONOMETRIC RECORDER 6Sheets-Sheet 6 Original FiledMarch 30, 1946 i T R I Q R i w\ g? m zINVENTOR zdbzam... W Y ,Zkfvyyk MW ATTORNEY Patented Jan. 24, 1950CHRONOMETRIC RECORDER William K. Coburn, Cambridge, Mass., assignor toSerdex, Inc., Boston, Mass, a corporation of Massachusetts Originalapplication March 30, 1946, Serial No. 658,556. Divided and thisapplication June 5, 1946, Serial No. 674,495

4 Claims.

The present invention relates to the art of transmitting intelligenceelectrically from a transmitter to a printing recorder and, in oneaspect, comprises a method of synchronizing a recorder with atransmitter. The present application is a division of my copendingapplication Serial No. 658,556 filed March 30, 1946, now Patent2,426,145, patented August 19, 1947, for improvements in Chronometricrecorder.

It has long been recognized that indications of coming weatherconditions are to be found in the movement of air masses aloft, asreflected in terms of pressure, temperature, and humidity at variouslevels. One satisfactory method for obtaining such data has been torelease a balloon carrying a small radio transmitter automatically keyedby elements'responsive to changes in temperature, pressure, and humidityand operating in turn to send series of signals to a receiver on theground. At the ground station the signals are impressed on a recordinginstrument which marks a sheet of moving paper at intervals appropriateto form a code or system of marks against scales graduated in terms ofthe data required.

' The transmitter is keyed by styli connected to the weather responsiveelements and playing over'a drum presenting a helix of wire on itsperiphery and driven by a constant speed motor. The recorder at theground station includesa similardrum and helix and a tapper bar arrangedto presstogether, and against the helix, superposed sheets of carbonpaper and scaled or graph paper. The tapper bar is actuated by thesignals received from the balloon transmitter. The'accuracy of aradiosonde's'ystem includ ing a chronometric recorder of the typedescribed depends to a great extent upon the maintenance of precisesynchronization between the balloon helix drum and the recorder helixdrum. It is, of course, impossible to control the speed of the motordriving the drum in a released balloon. Therefore it is the recorderdrive which must be capable of adjustment. By providing the balloonhelix drum with means for sending -a reference signal through thetransmitter at-a predetermined point in the revolution of the, helix,preferably at the beginning of each cycle, we

are able to obtain accurate information as to changes in the rate of thetransmitter helix. Thelproblem then becomes one of'devisin'g a .variablespeed drive for the recorder helix and of Ccouplingwith it'asufficiently accurate'speed controlling system. If-the's'e obstacles aresu cess-- fully overcome, accurate synchronization of the helices isrendered possible. 1

The entire cycle includes, in addition to the reference signal, signalsresponsive to the elements sensitive to pressure temperature andhumidity. The sequence in which the signals are received ispredetermined. It will be appreciated that if the recorder cycle were tobe started by a signal other than the reference signal, the record wouldbe unintelligible. If, for example, a pressure signal acted as areference signal, the cycle as printed would not be the cycle astransmitted from the balloon. Furthermore it is only the referencesignals which are spaced at uniform intervals; the information signalshave no predetermined interval and could not be used as the basis forsynchronizing the recorder.

The most important object of my invention is to improve the efficiencyof radiosonde meteor.- ology and make it possible to obtain accurate andimmediate reports relating to conditions aloft. Another object of myinvention is to improve the recording of weather data received fromradiosonde transmitters.

Still another object of the invention is to provide a method foraccurately synchronizing a recorder drive with the drive of any kind ofapparatus in communication electrically with the recorder. 3

One feature of the invention resides in a novel method for synchronizinga radiosonde transmitter helix with a recorder helix, including thesteps of operating the recorder helix at a slightly greater rate thanthe transmitter helix, stopping the recorder helix after one revolution,then inserting in the drive for the recorder helix a correctioncorresponding to its loss or gain in rate with respect to thetransmitter helix during'the cycle, and starting the recorder helixagain simultaneously with the initiation of another revolution of thetransmitter helix.

Another feature of the invention resides in apparatus for automaticallycarrying out the method outlined in the preceding paragraph.

3 These and other objects and features of the invention and theadvantages incident thereto will be more readily understood andappreciated from the following detailed description of preferredembodimentsthereof selected for purposes of illustration and shown inthe accompanying drawings, in which: Fig. 1 is a plan view of a recorderconstructed 'according to the invention,

Fig. 2 is a view in cross-section along the line 2-2 of Fig. 1,

Fig. 3 is a view in front elevation of the synchronizer dial withpointers removed,

Fig. 4 is a plan view showing the adjusting means for the helix stop camswitch,

Fig. 5 is a view, partly diagrammatic, in side elevation of the helixstop cam and switch,

Fig. 6 is a, block diagram of the elements of the recorder,

Fig. 7 is a circuit diagram for a manually controlled synchronizedrecorder, and

Fig. 8 is a circuit diagram for an automatic synchronizer for therecorder.

Before proceeding to a description of the recorder I shall discussbriefly the nature of the unit carried by the balloon. I have not shownsuch a unit in the drawings because my invention may be applied to anyof the commonly used types of balloon transmitter units. Such a unitincludes a frame-mounting a clockwork mechanism or motor driving acylindrical drum which is wound on the surface with a single helix ofwire. In the language of the art the drum and the wire are knowncollectively as the helix."

Poised in contact with the periphery of the drum at intervals are threemetal styli worked to slide axially alongthe drum by means of linkagesoperated respectively by elements responsive to temperature, pressure,and humidity. The frame carries a small transmitter powered by batteriesand .so connected to the helix and the styli that the continuous waveemitted by the transmitter is momentarily interrupted whenever one ofthe styli touches the wire of i the helix. Furthermore a contact membertouches the wire at the zero point in the rotation of the drum to causethe transmitter to send out a reference or synchronizing signal employedat the .ground station for tying in a recorder, as will presently apear..The styli are so arranged that they touch the wire in predeterminedorder once during each cycle. Consequently, there are four signalsbroadcast per cycle, i. e. a reference signal first, and then signalsrepresenting tem-,;

perature, pressure, and humidity.

Coming now to the ground station and to the apparatus comprising myinvention, I provide a conventional radio receiver tuned to thefrequency of the balloon transmitter and connected to a recorder. Themechanical aspect of the recorder is represented particularly in Figs. 1and v2 wherein I have shown a metal base Ill provided with parallel sidewalls I2 and on end wall I4.

A drum I6 of Bakelite, or other suitable materia'l is provided on itsperiphery with a helix I! of heavy gauge wire fitted in a groove and .sowound as to make one complete 360 spiral on the drum. A shaft I8journalled in the walls I2 ,is-keyed to the drum I6 and carries at oneend a flexible diaphragm 22 of ferrous metal .disposed between a pair ofspaced housings 24 and 25 within which are wound coils of wire'l3 and--.I5. The inner housing 24 is fastened to the wall I2, while the outerhousing 26 is secured to the end of a shaft 28 journalled in a metalwall or housing 29 and driven through a set of reduction gears 30 from amotor 32.

The housings '24 and 26 with their coils act as a magnetic clutch andbrake assembly. When the coil in the housing 24 is energized, thediaphragm 22 is pulled against the housing 24 and the drum isrbraked,Conversely when the coil in the housing 26 is energized, the diaphragmis pulled 5 Synchronous drive for bothrreels.

4 against the housing 26 and causes the drum to turn with the shaft 28.

The motor 32 also drives a set of reduction gears 34 which drive a shaft35 journalled in the wall 29 and provided with a bevel gear 38 in meshwith a second bevel gear 40 carried on a shaft 42 having a reduced end43 extending through a cylindrical housing 44. The housing 44 is fast toa worm wheel 45 driven by a worm (not shown) controlled by a hand wheel48. On theend of the shaft 43 is secured a block 4| on which is mounteda neon bulb 45. Also secured to the block is an opaque dial or bezel 41provided opposite the neon bulb 45 with a radial slit 41. The block 4|also carries a wiper contact or pointer 2I6 which bears against anannulus 49 of Bakelite or other insulating material interrupted at oneplace by a short metal slug or segment 222. The housing carries a glassdial or bezel 5| provided around its periphery with numerals from I toI5, at equally spaced intervals.

When the motor 32 turns the shaft 42, the rota-. tion of the shaftportion 43 rotates the block 41 and the elements secured thereon. Thusthe pointer 2I5 wipes around the surface of the Bakelite annulus 49which is secured to the housing 44 and does not move. However, the handwheel 48 may be manipulated to turn the housing 44 with respect to theblock 41. The operation of this portion of the mechanism can best beappreciated and understood inv connection with the discussion of thecircuit diagram which follows later.

Secured to the helix drive shaft .IB adjacent one end thereof is a diskcam member 21 provided in its periphery with a shallow depression orvalley 23 and cooperating with a switch control member25 mounted ina'block '21 adjustably secured to the side wall I2. As shown in Fig. 4the block 21 may be adjusted along a horizontal path by means of a setscrew 31 working in a lug secured to the wall l2. The block 21 is alsocontrolled by a set screw 33 which may be adjusted to vary the verticalposition of the assembly with respect to the cam wheel 2|. The functionof the cam wheel H is to operate the switch 25 to stop the-rotation ofthe helix through means best understood in connection with thedescription of the circuit diagram in Fig. '7.

Adjustably mounted in the side walls I2 is 1 pair of oppositely disposedtapper bar assembly "supports 50, each of which carries a metal endpended a pair of springs carrying a knife edged tapper bar 62. At theends of the tapper bar 62 is secured a pair of levers '64, which work onpivot points 66 set in the walls 52, and are bent to extend beneath thesolenoids 56.

Rotatably mounted between the walls I2 behind and below the tapper barassembly is a reel "for carbon paper which advances from the reel over aguide 59, between the drum I 6 and the tapper bar '52, upwardly acrossthe vertically aligned guide rollers 10, and rearwardly across .anotherpair of rollers 12 and 14 to a collecting 7 reel 15 also 'rotatablymounted between the side walls I2. A motor 11 secured to the base I! isprovided with a sprocket carrying a chain I8 which drives the reel 68.Asimilar chain runs on sprockets rm the reel! 68, and I6 to provide aBelow and in front of the drum is mounted a reel 84 for plain or scaledrecord-receiving paper 63 which advances from the reel to the drum I6adjacent the guide 69 where it is led beneath the carbon paper 65leaving the reel 68. The two papers move together beneath the tapperbar, but the scaled paper then moves over a table 92 and over a pair oftoothed wheels 88 keyed to a transverse shaft 86 driven by a chain 82which also drives the reel 84. A pair of toothed idlers 90 are mountedon the shaft I8 for assisting the feeding of the papers. The teethengage perforations in the margins of the paper and serve to prevent thepaper from sliding from side to side.

The switches for the motors 32 and 31 are contained in housings 96secured to the rear wall I4. A terminal block 98 is also mounted on thisrear wall.

One circuit for driving the recorder-elements is illustrated in theblock diagram, Fig. 6, wherein it will be seen that a variable frequencyoscillator (of conventional design), coupled to a power supply unit,serves to drive the motor 32, the speed of which is to be synchronizedwith the transmitter helix in the balloon. By varying the oscillatorfrequency the operator may vary the speed of the motor 32, and a knob Iis shown for the purpose of indicating the manner in which theoscillator frequency may be varied.

The receiver (not shown) is connected to a sig: nal relay which in turnis connected to the tapper bar'circuit and to the synchronizer. Thelatter is represented by the pointer I02 arranged to be rotated byshafts and gearing from the motor 32. A segment I04 disposed in the dialin position to be swept by the pointer is connected to a start relayarranged to actuate the magnetic clutch when the reference signal comesfrom the receiver and provided the pointer I02 is in contact with thesegment I04. When the helix I8 has completed one revolution, the stopcam 2| opens the switch 25 to actuate a stop relay which deenergizes themagnetic clutch and energizes the magnetic brake.

The gearing is such that, it requires fifteen seconds for the pointer tocomplete a revolution, but the helix is arranged to complete itsrevolution in fourteen seconds. Consequently, there is a rest periodduring which the operator may manipulate the knob I00 to change thespeed of the motor to bring the pointer into synchronization with thereference signals received from the transmitter helix.

With this general explanation in mind the reader can better appreciatethe operation of the circuit shown in Fig. 7. Here again the helix I5 isdriven through a magnetic clutch and brake comprising a diaphragm 200carried on the end of the helix shaft 202 and disposed between a clutchcoil 204 and a brake coil 206. One side of each coil is grounded. Ashaft 208, which drives the clutch housing, is driven from a motor 2I0corresponding in function to that of the motor 32 in Fig. 6 which inturn is driven from a variable frequency oscillator 2I2. A control knob2I4 is provided for manually varying the oscillator output frequency. Apointer 2I6 is driven from the motor 2I0 through a shaft 2 I8 and sweepsa dial 220 having a contact segment 222. A neon bulb 224 is connectedacross the pointer and the segment, the circuit including a switch 226controlled by a latching relay 228 one side of which is adapted to begrounded through the segment 2229 1101 the pointer 2I6. The other sideofthe latching relay 228 is connected to a switch 230 controlled by arelay 232 which forms the load for the ground radio receiver (notshown). A second switch 234 is coupled to the relay 232 and actuates thetapper bar circuit.

When a signal is applied from the receiver to the relay 232 the tapperbar is actuated through the switch 234. If the pointer2 I 6 is then incontact with the segment 222, th neon bulb 224 flashes. However, therelay 228 is also energized to open the switch 226 and extinguish thebulb at once. The relay 228 is of the type which is latched when animpulse reaches it, with the result that the bulb 224 cannot flash againuntil the relay releases the switch 226 and another impulse operates therelay 232.

When the switch 230 is closed by the relay 232, a circuit is formedstarting from the positive ter-- minal of the volt battery shown at theextreme right of the wiring diagram of Fig. 7, proceeding through theswitch contacts 230, through the solenoid coil for the relay 228, thento the segment 222, through the pointer 2I6, to ground. In this circuitthe coil of the relay 228 serves as the load.

When the relay 228 is energized it pulls closed a switch 238 whichcloses a circuit through the magnetic clutch and including a source of90 volt current. The helix then begins to revolve, the

switch member 25 rides out of the valley on the stop cam 2I and acircuit is closed including a relay 240 which controls a switch 242connected across the 90 volt source and the magnetic clutch coil 204.

When the helix completes one revolution the switch 25 opens as themember falls into the valley 23. The relay 240 is actuated to open theswitch 242, and close a switch 244. The latter switch controls anunlatchin relay 245 which in turn operates a switch 246 controlling thecircuit to the magnetic brake coil 206. The relay 245 is ganged with therelay 228 so that energization of the relay 245 not only actuates themagnetic brake but also unlatches the relay 228 causing the switch 236to open the circuit to the magnetic clutch.

In order to provide a check on the operation of the circuits abovediscussed, I connect a lamp 250 across the clutch control circuit toground, preferably a green lamp; similarly a red lamp 252 may beconnected across the brake control circuit to ground. Consequently, theoperator of the equipment is enabled to determine visually which circuitis energized.

If a signal operates the relay 232 when the pointer 2", is notin'contact with the segment 222 the neon bulb 224 will flash and thetapper bar will be actuated. However, the relay 228 will not beactuated, and the brake will remain on. The resistance across the neonbulb is great enough to prevent actuation of the relay 228, although thebulb will flash. The red light 252 will remain on, and the light 250will remain extinguished. By observing the relation of the pointer 2I6to the segment 222 through the the slit 4'! (Fig. 3) the operator candetermine whether to speed up the motor 2I0 or slow it down. He thenmanipulates the control knob 2I4 to vary the oscillator output frequencyuntil the speed of the pointer matches the speed of the transmitterhelix. The first step, of course, is to manipulate the hand wheel 48 toget a reference signal to coincide with the juxtaposition of the pointerand the segment.

The gearing is such that the helix :rotates asaaoea faster than thepointer .213, while the latter is set to run at thesame speed as thetransmitter helix. For example, the latter two may be set to turn at 4R. P. M. and the recorder helix at 4.2 R. P. M. Consequently the helix16 will stop when the pointer 21!; and transmitter helix have completedapproximately 90% .of a revolution. The waiting period may be used toapply the proper speed correction to the oscillator so that the ensuingcycle of the pointer will exactly match that :of the transmitter helix.

' The speed of the transmitter helix changes unavoidably as the balloonincreases altitude. However, the change is generally very gradual, andan operator may be trained in a short time to assess the changes andoperat the frequency control knob in proper fashion.

The foregoing discussion has related to refer ence signals. It will beobvious that the appa ratus is set up so that the reference signal willoperate the various relays in the manner described, based on theconjunction of the pointer and segment. The information signals come inwhen the pointer and segment are not in contact and the only effect isto actuate the tapper bar.

If no reference signal is received, the helix will not revolve, and theactuation of the tapper bar does no harm.

The recorder described above requires a trained operator to run itproperly. invented an automatically synchronized recorder which requiresonly to be set in operation properly and will thereafter continue byitself with out attention.

The circuit for the automatically synchronized recorder is shown in Fig.8. As before, I utilize a helix driven by a motor similar to the motor210 controlled by a variable frequency oscillator similar to theoscillator 212. The elements which are not shown in Fig. 8 correspond tothose shown in the other figures. In this case I provide a dial havingtwo pointers 300 and 302 in sulated from each other and angularlyoffset: The pointer 300 wipes across a series of commutator segments 304separated by blocks 306 of insulating material. The pointer 302 wipesacross a segment 308 dimensioned to cover 12 of the pointer rotation.The output of the receiver (not shown) is connected across the pointer3G2 and the segment 308 and includes a relay 310 controlling a switch3I4 and a switch 3|2; Unless the pointer 302 is touching the segment 308when a signal comes through, the relay 3l0 will not be actuated.

The switch 3l4 controls the tapper bar circuit, while the switch 3 [2controls a relay 320 arranged to operate a stepping switch 322 providedwith a cam wheel 324 actuating a nine gang'switch 326'. The gang switch326 is always connected to the variable frequency oscillator and isalternately connected to one of a pair of stepping relays A and B. Eachof the relays A and B includes a switch member comprising a toothedwheel 328 (328') (hereinafter sometimes referred to as the switchitself) actuated a dog 330 (330) operated by a solenoid 332 '(332'). Thesolenoids 332 and 332' are connected alternately through thegang switch326 to the pointer 300, and the commutator segments 304 are connected toa' battery 340 through a switch 342 controlled by the helix stop cam 2i.The battery 340 is also connected to one side of therela-ys 332 and332'. The helix stop cam 2| also controls 'a switch 345 which actuatesthe clutch and {brake in the manner shown inFig. 'l; 1 V j However, Ihave also Assuming that the switch 1323 is in posltimtto put the relay.A in the circuit, the pointer 30' will transmit a pulse to the solenoid332 each time it wipes across one of the commutator seg: ments 304.Consequently the dog 330 will oper: ate to step the wheel 328 by onetooth every time the relay pulses. The relay A controls two banks ofresistors R and S through a pair of rotating contact members 350 and352. Each bankof resistors R and S may be connected through the switch326 .to the variable frequency oscillator, and the arrangement is suchthat when the solenoid 332 is connected to the pointer 300, the banks ofresistors R .and S of the relay B are connected to the oscillator, andthe contacts 350' and 352' are at rest to connect into the oscillatorcircuit a given pair of resistors, one from each of the banks R and S.The resistors are included in the oscillator circuit with the otherelements thereof, and their value determines the frequency of theoscillator output. Obviously the resistors could bereplaced by inductorsor'capacitors of suitable values in order to effect a similar result.

When the helix completes a revolution, the switch member 25 falls intothe valley 23 opening the switch 342, thus preventing the pointer 300from sending impulses tothe relays A or B. The member 25 also operatesto de-energize the magnetic clutch and energize the brake, as cussed inconjunction with Fig. 7-; the clutch and brake coils and relays do notappear in Fig. 8.

The pointers 300 and 302 have not finisheda revolution when the helix isstopped but continue until they arrive at the zero position once more.The segment 308 covers approximately six de grees either side of thezero point. Consequently; the following reference signal will actuatethe circuit even though it be a trifle oil the zero point.

Synchronization is obtained in the following manner. Assume that relay.A is in control of the oscillator, i. e. the solenoid 332 is disconnected but the resistor banks R and S are con: nected to the oscillatorthrough the switch 326; One resistor in each bank is thus included inthe oscillator circuit and the pair determines the speed of the motor.The banks R and S are disconnected but the solenoid 332' -is energizedby. pulses transmitted from the pointerf300. The resistors, the wheels328 and 328 and the 0on5 tacts 350, 350, 352, and 352 are so operatedthat if the pointer 300 is exactly synchronized with the transmitterhelix, the resistor terminals touched by the contacts 350' and 352' atthein stant the cycle ends will be the same in value as the resistors inthe banks R and S which governed the speed of that cycle of the pointerand helix. While I have shown a circuit in which resistors are used asthe elements by means of which the frequency of the oscillator ischanged. I may employ any suitable type of impedance for the samefunction. For example the banks of resistors might be replaced by banksof'cori' dcnsers or inductances. If the pointer 300 S slower than thetransmitter helix, the pointer will have travelled less than 360when'th'e next reference signal comes in. (The helix, of course; stopswhen the pointer reaches about 324" of its revolution.) The referencesignal will therefore operate the solenoid 332 to disconnect banks-R andS and the solenoid 332 and connect in the banks R and S before thesolenoid 332 has conic to the point of causing the contacts 350' and352" to touch the terminals of resistors having-the sameyalue as thosein the-banks R and Swhlch 9 governed the speed of the first cycle. Thedifferent resistors now connected in from the banks R and S will be justenough different in value to increase the oscillator frequencysufiiciently to match the speed of the pointer 3th to that of thetransmitter helix. To recapitulate somewhat, the circuit is so arrangedthat the frequency of the output of the variable frequency oscillator isa function of the values of two resistors. By providing a pair of banksof resistors of different values, I am able to determine the frequencyof the oscillator by selecting one resistor from each bank andconnecting it appropriately into the circuit of the oscillator. Theswitching in of the pair of resistors in the case of the banks R and Sis controlled by the stepping switch 328. The resistors in the banks Rand S are counterparts of those in the banks R and S and the switch 328is the counterpart of the switch 328. The gang switch 326 is arranged togive control of the oscillator alternately to the R and S bank and tothe R and S bank. As explained above, while a pair of resistors from thebanks R and S are functioning in the oscillator circuit, the step switch328 is being operated to select from the R and S bank the proper pair ofresistors to govern the oscillator during the next cycle of theequipment. In other words, each assembly is either governing theoscillator or being placed in a condition to govern the oscillatorduring the next cycle.

Similarly if the pointer 3% travels faster than the transmitter helix,it will have travelled more than 360 when the second reference signalcomes in. The wheel 328 or 328, depending on the position of the switch326, will connect in the proper values of resistors from one set ofbanks to slow down the motor by lowering the oscillator outputfrequency. I have found that by includ synchronizing circuit out ofoperation. As explained above, the increments of speed change from cycleto cycle are so small that my system can easily accommodate the changesaccumulated in several missed cycles.

The relays A and B are self-cycling, a feature which becomes ofimportance only when for some reason the reference signal is notreceived. When this happens the switch 326 will not operate to changethe connections to the relays A and B, but the self-cycling featurecomes into play with the result that one of the wheels 328 and 328 whichwas doing the moving during the preceding cycle will fly back to theposition it had at the start of its preceding cycle, thus connecting thecontacts 350 350), and 352 (352) to the set of resistors equalling thevalue of those controlling the oscillator during the penultimate cycle.The circuit will then be ready to operate upon the receipt of the nextreference signal.

It should be pointed out that the automatic synchronizing circuit shownin Fig. 8, or the manual control circuit shown in Fig. '7, may be usedto synchronize instrumentalities other than a recorder for radiosonde.For example, either circuit may be used to synchronize theinstrumentalities of a facsimile transmitting and receiving system.Those skilled in the art will appreciate many modifications andapplications of the invention shown in the embodiments selected fordetailed description herein.

Having now described and illustrated preferred embodiments of myinvention, what I claim as new and desire to secure by Letters Patent ofthe United States is:

1. Method of synchronizing the rate of drive of a radiosonde transmitterhelix and a radiosonde recorder helix, which comprises mechanicallydriving the recorder helix at a speed greater than that of thetransmitter helix by a small fixed amount, starting the cycles of thehelices simultaneously, stopping the recorder helix when it has made onecomplete revolution and before the transmitter helix has completed arevolution, measuring the difference in the speeds of the recorder helixand the transmitter helix, varying the rate of drive or" the recorderhelix by the measured amount, and then initiating another cycle of bothhelices simultaneously without stopping the transmitter helix.

2. The method of synchronizing radiosonde transmitter and recorderhelices, which comprises mechanically driving the recorder helix fasterthan the transmitter helix, stopping the recorder helix after onerevolution, then prior to the completion of a revolution by thetransmitter helix measuring the difference in the speeds of the helicescorresponding to the loss or gain in rate of the recorder helix withrespect to the transmitter helix during the cycle, varying the rate ofthe recorder helix by the measured amount, and starting the recorderhelix simultaneously with the initiation of another revolution by thetransmitter helix.

3. The method recited in claim 2 wherein the steps are repeated once forevery revolution of the transmitter helix.

4. The method of synchronizing a transmitter and a recorder in which thetransmitter includes a motor driven keying device and the recorderincludes a motor driven printing device, which comprises mechanicallydriving the printing device faster than the keying device, stopping theprinting device after one cycle, then prior to the completion of arevolution by the keying device measuring the difference in the speedsof the helices corresponding to the loss or gain in rate of the recorderhelix with respect to the keying device during the cycle, varying therecorder helix rate by the measured amount, and starting the printingdevice cycle simultaneously with the initiation of another revolution bythe keying device.

WILLIAM K. COBURN.

REFERENCES CITED UNITED STATES PATENTS Name Date Turner et a1. May 25,1937 Number

